Display apparatus with densely packed electromechanical systems display elements

ABSTRACT

This disclosure provides systems, methods and apparatus for reducing undesired capacitance and electrostatic attraction among components of electromechanical systems (EMS) displays. An apparatus includes an array of display elements, a control matrix, and an electric insulation layer. The display elements each include a movable light blocking component coupled to a conductive beam. The control matrix includes a plurality of interconnects, including at least one switched interconnect, which passes under and is electrically isolated from at least one of the conductive beam and the movable light blocking component

TECHNICAL FIELD

This disclosure relates to the field of displays, and in particular, todisplays that include switched interconnects routed underneath suspendedcomponents of electromechanical systems (EMS) display elements.

DESCRIPTION OF THE RELATED TECHNOLOGY

Electromechanical systems (EMS) devices, and larger scale devices, havebeen incorporated into a variety of display devices to modulate light.Some EMS light modulators include components that are suspended over thesubstrate on which they are fabricated and are configured to move in aplane substantially parallel to the substrate.

Generally, displays with such architectures have forgone routingelectrical interconnects underneath these suspended components to limitthe risk that the electrical fields generated from current passingthrough the interconnects would result in electrostatic attractionbetween the suspended components and the interconnects. Such attractioncould potentially draw the components into contact with the substrate orother intervening display components, where they might permanentlyadhere as a result of static friction or stiction. Routing theinterconnects beneath the suspended components also increases theopportunity for parasitic capacitance on the interconnects. Thisincreased capacitance results in additional power being needed tooperate the display, and slows down its addressing and/or actuationtime.

To avoid these potential problems, such displays have routed theirinterconnects between display elements, such that they do not pass underany suspended display element components. While doing so mitigates therisk of stiction and reduces capacitance on the interconnects, placingthe interconnects between display elements takes up significantsubstrate real-estate, limiting the packing density and/or the apertureratio of the display elements.

SUMMARY

The systems, methods and devices of the disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

One innovative aspect of the subject matter described in this disclosurecan be implemented in an apparatus that includes an array of displayelements, a control matrix, and an electrical insulation layer. Each ofthe display elements has suspended components, including a movable lightblocking component and a conductive beam coupled to the movable lightblocking component. The control matrix includes a plurality ofinterconnects. The interconnects include at least one switchedinterconnect which couples to portions of a plurality of the displayelements in the array, passes under at least one of the conductive beamand the movable light blocking components, and which is electricallyisolated from the movable light blocking components. The electricalinsulation layer has a thickness greater than about 1 micron and lessthan about 5 microns, and is disposed between the at least one switchedinterconnect and the suspended components of the display elements.

In some implementations, the electrical insulation layer can be disposedbetween an uppermost interconnect of the control matrix and thesuspended components of the display apparatus. In some implementations,the conductive beam of each of the display elements is coupled to ananchor, and the electric insulation layer is disposed under the anchorssupporting the conductive beams of the display elements.

In some implementations, the electric insulation layer has a thicknessof greater than about 1.5 microns and less than about 4 microns. In someother implementations, the electrical insulation layer has a thicknessof greater than about 2 microns and less than about 4 microns. In someimplementations, the electric insulation layer is light absorbing. Insome other implementations, the electric insulation layer issubstantially transparent.

In some implementations, the apparatus includes a light blocking layerpositioned between the light-blocking components and a backlight. Insome such implementations, the switched interconnect can be disposedover the light blocking layer. In some implementations, the lightblocking layer includes a plurality of openings, and the light blockingcomponent of each display element is configured to move into and out ofalignment with a corresponding opening in the light blocking layer. Insome implementations, the electric insulation layer extends over theplurality of openings.

In some implementations, the switched interconnect is either a datainterconnect, a write-enabling interconnect, or an actuation voltageinterconnect. In some implementations, the switched interconnectincludes an interconnect coupled to display elements in multiple rowsand multiple columns of the array of display elements.

In some implementations, the apparatus of includes a display, aprocessor that is configured to communicate with the display, theprocessor being configured to process image data, and a memory devicethat is configured to communicate with the processor. In someimplementations, the display also includes a driver circuit configuredto send at least one signal to the display and a controller configuredto send at least a portion of the image data to the driver circuit. Insome other implementations, the apparatus the display also includes animage source module configured to send the image data to the processor.The image source module may include at least one of a receiver,transceiver, and transmitter. The display may also include an inputdevice configured to receive input data and to communicate the inputdata to the processor.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a display device. The display deviceincludes an array of display elements, a control matrix, and a means forreducing the strength of an electric field. The array of displayelements includes light modulating means. The control matrix includes aplurality of interconnects, including at least one switched interconnectwhich couples to portions of a plurality of the display elements in thearray, passes under at least a portion of the light modulating means,and which is electrically isolated from the light modulating means. Themeans for reducing the strength of an electric field is configured toreduce the strength of the electric field emanating from the switchedinterconnect on the light modulating means.

In some implementations, the light modulating means includes a lightblocking shutter suspended over a substrate by a compliant beam. Themeans for reducing the strength of the electric field may include anelectric insulation layer disposed between the switched interconnect andthe light modulating means. The thickness of the electric insulationlayer may be greater than about 1 micron and less than about a 5microns.

In some implementations, the display device may also include a means forreducing the capacitance of the interconnects in the control matrix. Themeans for reducing capacitance may be the same as, or include the meansfor reducing the strength of the electric field.

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Although the examples provided in this summary areprimarily described in terms of MEMS-based displays, the conceptsprovided herein may apply to other types of displays, such as liquidcrystal displays (LCDs), organic light emitting diode (OLED) displays,electrophoretic displays, and field emission displays, as well as toother non-display MEMS devices, such as MEMS microphones, sensors, andoptical switches. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows an example schematic diagram of a direct-viewmicroelectromechanical systems (MEMS) based display apparatus.

FIG. 1B shows an example block diagram of a host device.

FIG. 2A shows a perspective view of an example shutter-based lightmodulator.

FIG. 2B shows an example cross sectional view of an illustrative nonshutter-based MEMS light modulator.

FIG. 3A shows an example schematic diagram of a control matrix.

FIG. 3B shows a perspective view of an example array of shutter-basedlight modulators connected to the control matrix of FIG. 3A.

FIGS. 4A and 4B show example views of a dual actuator shutter assembly.

FIG. 5 shows an example cross sectional view of a display apparatusincorporating shutter-based light modulators.

FIG. 6 shows a cross sectional view of an example light modulatorsubstrate and an example aperture plate for use in a MEMS-downconfiguration of a display.

FIG. 7 shows a plan view of an example array of EMS display elements.

FIGS. 8-11 show cross sectional views of example display apparatusincorporating the array of display elements shown in FIG. 7.

FIGS. 12 and 13 are example system block diagrams illustrating a displaydevice that includes a plurality of display elements.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

The following description is directed to certain implementations for thepurposes of describing the innovative aspects of this disclosure.However, a person having ordinary skill in the art will readilyrecognize that the teachings herein can be applied in a multitude ofdifferent ways. The described implementations may be implemented in anydevice, apparatus, or system that can be configured to display an image,whether in motion (such as video) or stationary (such as still images),and whether textual, graphical or pictorial. More particularly, it iscontemplated that the described implementations may be included in orassociated with a variety of electronic devices such as, but not limitedto: mobile telephones, multimedia Internet enabled cellular telephones,mobile television receivers, wireless devices, smartphones, Bluetooth®devices, personal data assistants (PDAs), wireless electronic mailreceivers, hand-held or portable computers, netbooks, notebooks,smartbooks, tablets, printers, copiers, scanners, facsimile devices,global positioning system (GPS) receivers/navigators, cameras, digitalmedia players (such as MP3 players), camcorders, game consoles, wristwatches, clocks, calculators, television monitors, flat panel displays,electronic reading devices (e.g., e-readers), computer monitors, autodisplays (including odometer and speedometer displays, etc.), cockpitcontrols and/or displays, camera view displays (such as the display of arear view camera in a vehicle), electronic photographs, electronicbillboards or signs, projectors, architectural structures, microwaves,refrigerators, stereo systems, cassette recorders or players, DVDplayers, CD players, VCRs, radios, portable memory chips, washers,dryers, washer/dryers, parking meters, packaging (such as inelectromechanical systems (EMS) applications includingmicroelectromechanical systems (MEMS) applications, as well as non-EMSapplications), aesthetic structures (such as display of images on apiece of jewelry or clothing) and a variety of EMS devices. Theteachings herein also can be used in non-display applications such as,but not limited to, electronic switching devices, radio frequencyfilters, sensors, accelerometers, gyroscopes, motion-sensing devices,magnetometers, inertial components for consumer electronics, parts ofconsumer electronics products, varactors, liquid crystal devices,electrophoretic devices, drive schemes, manufacturing processes andelectronic test equipment. Thus, the teachings are not intended to belimited to the implementations depicted solely in the Figures, butinstead have wide applicability as will be readily apparent to onehaving ordinary skill in the art.

Electromechanical systems (EMS) display apparatus and processes formanufacturing such display apparatus are disclosed herein. EMS displayapparatus include display apparatus that incorporatenanoelectromechancial systems (NEMS), microelectromechanical systems(MEMS), or larger scale EMS display elements. More particularly, thedisplay apparatus disclosed herein incorporate switched interconnectsthat are routed underneath suspended components of an array of EMSdisplay elements, such as light modulating shutters and compliant beamsthat form electrostatic actuators configured to move the shutter betweenstates. In various implementations, the switched interconnects mayinclude write-enabling interconnects, also referred to as scan-lineinterconnects, data interconnects, actuation voltage interconnects orglobal actuation interconnects.

To mitigate the impact of the electric fields emanating from theinterconnects, in some implementations a relatively thick layer ofelectrically insulating material, such as a dielectric, is depositedover the uppermost interconnect in the display apparatus. The layer ofdielectric material ranges from greater than about 1 micron to less thanabout 5 microns. This is in contrast to the thickness of a typicalinter-metal dielectric layer which ranges from about 0.1 microns toabout 1 microns.

In some other implementations, the display apparatus omits the thickerlayer of electrically insulating material. In such implementations, thedisplay apparatus includes taller anchors, which support the suspendedcomponents of the display apparatus a greater distance over theuppermost interconnect.

Particular implementations of the subject matter described in thisdisclosure can be implemented to realize one or more of the followingpotential advantages. In some implementations, routing displayinterconnects underneath suspended components of EMS display elementsincorporated therein allows for a tighter packing of display elements.This, in turn, allows for higher display resolution. Alternatively, suchrouting can allow for increased display aperture ratio.

Spacing the suspended components from the interconnects by a relativelythick layer of electrically insulating material reduces the strength ofthe electric field emanating from the interconnects. This reduces therisk of undesirable electrostatic attraction pulling the suspendedcomponents out of their intended plane of travel, which would increasethe risk of stiction between the suspended components and other displaycomponents.

Incorporation of the layer of electrically insulating material alsoadvantageously reduces the volume of fluid used to fill the displayapparatus. The risk of bubble formation in the fluid resulting fromambient temperature changes increases with the volume of the fluid usedto fill the device. Thus, filling space in the display apparatus withthe layer of electrically insulating material instead of additionalfluid reduces the likelihood of bubble formation.

Spacing the suspended components further away from the interconnectsalso decreases the capacitance between them. Such capacitance cansubstantially slow the propagation rate of signals along theinterconnects, as well as require additional power to operateeffectively. Thus, decreasing this capacitance increases the speed withwhich the display can be addressed and/or actuated, and also reduces thepower consumed by the display.

FIG. 1A shows a schematic diagram of a direct-view MEMS-based displayapparatus 100. The display apparatus 100 includes a plurality of lightmodulators 102 a-102 d (generally “light modulators 102”) arranged inrows and columns. In the display apparatus 100, the light modulators 102a and 102 d are in the open state, allowing light to pass. The lightmodulators 102 b and 102 c are in the closed state, obstructing thepassage of light. By selectively setting the states of the lightmodulators 102 a-102 d, the display apparatus 100 can be utilized toform an image 104 for a backlit display, if illuminated by a lamp orlamps 105. In another implementation, the apparatus 100 may form animage by reflection of ambient light originating from the front of theapparatus. In another implementation, the apparatus 100 may form animage by reflection of light from a lamp or lamps positioned in thefront of the display, i.e., by use of a front light.

In some implementations, each light modulator 102 corresponds to a pixel106 in the image 104. In some other implementations, the displayapparatus 100 may utilize a plurality of light modulators to form apixel 106 in the image 104. For example, the display apparatus 100 mayinclude three color-specific light modulators 102. By selectivelyopening one or more of the color-specific light modulators 102corresponding to a particular pixel 106, the display apparatus 100 cangenerate a color pixel 106 in the image 104. In another example, thedisplay apparatus 100 includes two or more light modulators 102 perpixel 106 to provide luminance level in an image 104. With respect to animage, a “pixel” corresponds to the smallest picture element defined bythe resolution of image. With respect to structural components of thedisplay apparatus 100, the term “pixel” refers to the combinedmechanical and electrical components utilized to modulate the light thatforms a single pixel of the image.

The display apparatus 100 is a direct-view display in that it may notinclude imaging optics typically found in projection applications. In aprojection display, the image formed on the surface of the displayapparatus is projected onto a screen or onto a wall. The displayapparatus is substantially smaller than the projected image. In a directview display, the user sees the image by looking directly at the displayapparatus, which contains the light modulators and optionally abacklight or front light for enhancing brightness and/or contrast seenon the display.

Direct-view displays may operate in either a transmissive or reflectivemode. In a transmissive display, the light modulators filter orselectively block light which originates from a lamp or lamps positionedbehind the display. The light from the lamps is optionally injected intoa lightguide or “backlight” so that each pixel can be uniformlyilluminated. Transmissive direct-view displays are often built ontotransparent or glass substrates to facilitate a sandwich assemblyarrangement where one substrate, containing the light modulators, ispositioned directly on top of the backlight.

Each light modulator 102 can include a shutter 108 and an aperture 109.To illuminate a pixel 106 in the image 104, the shutter 108 ispositioned such that it allows light to pass through the aperture 109towards a viewer. To keep a pixel 106 unlit, the shutter 108 ispositioned such that it obstructs the passage of light through theaperture 109. The aperture 109 is defined by an opening patternedthrough a reflective or light-absorbing material in each light modulator102.

The display apparatus also includes a control matrix connected to thesubstrate and to the light modulators for controlling the movement ofthe shutters. The control matrix includes a series of electricalinterconnects (such as interconnects 110, 112 and 114), including atleast one write-enable interconnect 110 (also referred to as a“scan-line interconnect”) per row of pixels, one data interconnect 112for each column of pixels, and one common interconnect 114 providing acommon voltage to all pixels, or at least to pixels from both multiplecolumns and multiples rows in the display apparatus 100. In response tothe application of an appropriate voltage (the “write-enabling voltage,V_(WE)”), the write-enable interconnect 110 for a given row of pixelsprepares the pixels in the row to accept new shutter movementinstructions. The data interconnects 112 communicate the new movementinstructions in the form of data voltage pulses. The data voltage pulsesapplied to the data interconnects 112, in some implementations, directlycontribute to an electrostatic movement of the shutters. In some otherimplementations, the data voltage pulses control switches, for example,transistors or other non-linear circuit elements that control theapplication of separate actuation voltages, which are typically higherin magnitude than the data voltages, to the light modulators 102. Theapplication of these actuation voltages then results in theelectrostatic driven movement of the shutters 108.

FIG. 1B shows an example of a block diagram of a host device 120 (i.e.,cell phone, smart phone, PDA, MP3 player, tablet, e-reader, netbook,notebook, etc.). The host device 120 includes a display apparatus 128, ahost processor 122, environmental sensors 124, a user input module 126,and a power source.

The display apparatus 128 includes a plurality of scan drivers 130 (alsoreferred to as “write enabling voltage sources”), a plurality of datadrivers 132 (also referred to as “data voltage sources”), a controller134, common drivers 138, lamps 140-146, lamp drivers 148 and an array150 of display elements, such as the light modulators 102 shown in FIG.1A. The scan drivers 130 apply write enabling voltages to scan-lineinterconnects 110. The data drivers 132 apply data voltages to the datainterconnects 112.

In some implementations of the display apparatus, the data drivers 132are configured to provide analog data voltages to the array 150 ofdisplay elements, especially where the luminance level of the image 104is to be derived in analog fashion. In analog operation, the lightmodulators 102 are designed such that when a range of intermediatevoltages is applied through the data interconnects 112, there results arange of intermediate open states in the shutters 108 and therefore arange of intermediate illumination states or luminance levels in theimage 104. In other cases, the data drivers 132 are configured to applyonly a reduced set of 2, 3 or 4 digital voltage levels to the datainterconnects 112. These voltage levels are designed to set, in digitalfashion, an open state, a closed state, or other discrete state to eachof the shutters 108.

The scan drivers 130 and the data drivers 132 are connected to a digitalcontroller circuit 134 (also referred to as the “controller 134”). Thecontroller sends data to the data drivers 132 in a mostly serialfashion, organized in predetermined sequences grouped by rows and byimage frames. The data drivers 132 can include series to parallel dataconverters, level shifting, and for some applications digital to analogvoltage converters.

The display apparatus optionally includes a set of common drivers 138,also referred to as common voltage sources. In some implementations, thecommon drivers 138 provide a DC common potential to all display elementswithin the array 150 of display elements, for instance by supplyingvoltage to a series of common interconnects 114. In some otherimplementations, the common drivers 138, following commands from thecontroller 134, issue voltage pulses or signals to the array 150 ofdisplay elements, for instance global actuation pulses which are capableof driving and/or initiating simultaneous actuation of all displayelements in multiple rows and columns of the array 150.

All of the drivers (such as scan drivers 130, data drivers 132 andcommon drivers 138) for different display functions aretime-synchronized by the controller 134. Timing commands from thecontroller coordinate the illumination of red, green and blue and whitelamps (140, 142, 144 and 146 respectively) via lamp drivers 148, thewrite-enabling and sequencing of specific rows within the array 150 ofdisplay elements, the output of voltages from the data drivers 132, andthe output of voltages that provide for display element actuation. Insome implementations, the lamps are light emitting diodes (LEDs).

The controller 134 determines the sequencing or addressing scheme bywhich each of the shutters 108 can be re-set to the illumination levelsappropriate to a new image 104. New images 104 can be set at periodicintervals. For instance, for video displays, the color images 104 orframes of video are refreshed at frequencies ranging from 10 to 300Hertz (Hz). In some implementations the setting of an image frame to thearray 150 is synchronized with the illumination of the lamps 140, 142,144 and 146 such that alternate image frames are illuminated with analternating series of colors, such as red, green, and blue. The imageframes for each respective color is referred to as a color subframe. Inthis method, referred to as the field sequential color method, if thecolor subframes are alternated at frequencies in excess of 20 Hz, thehuman brain will average the alternating frame images into theperception of an image having a broad and continuous range of colors. Inalternate implementations, four or more lamps with primary colors can beemployed in display apparatus 100, employing primaries other than red,green, and blue.

In some implementations, where the display apparatus 100 is designed forthe digital switching of shutters 108 between open and closed states,the controller 134 forms an image by the method of time division grayscale, as previously described. In some other implementations, thedisplay apparatus 100 can provide gray scale through the use of multipleshutters 108 per pixel.

In some implementations, the data for an image state 104 is loaded bythe controller 134 to the display element array 150 by a sequentialaddressing of individual rows, also referred to as scan lines. For eachrow or scan line in the sequence, the scan driver 130 applies awrite-enable voltage to the write enable interconnect 110 for that rowof the array 150, and subsequently the data driver 132 supplies datavoltages, corresponding to desired shutter states, for each column inthe selected row. This process repeats until data has been loaded forall rows in the array 150. In some implementations, the sequence ofselected rows for data loading is linear, proceeding from top to bottomin the array 150. In some other implementations, the sequence ofselected rows is pseudo-randomized, in order to minimize visualartifacts. And in some other implementations the sequencing is organizedby blocks, where, for a block, the data for only a certain fraction ofthe image state 104 is loaded to the array 150, for instance byaddressing only every 5^(th) row of the array 150 in sequence.

In some implementations, the process for loading image data to the array150 is separated in time from the process of actuating the displayelements in the array 150. In these implementations, the display elementarray 150 may include data memory elements for each display element inthe array 150 and the control matrix may include a global actuationinterconnect for carrying trigger signals, from common driver 138, toinitiate simultaneous actuation of shutters 108 according to data storedin the memory elements.

In alternative implementations, the array 150 of display elements andthe control matrix that controls the display elements may be arranged inconfigurations other than rectangular rows and columns. For example, thedisplay elements can be arranged in hexagonal arrays or curvilinear rowsand columns. In general, as used herein, the term scan-line shall referto any plurality of display elements that share a write-enablinginterconnect.

The host processor 122 generally controls the operations of the host.For example, the host processor 122 may be a general or special purposeprocessor for controlling a portable electronic device. With respect tothe display apparatus 128, included within the host device 120, the hostprocessor 122 outputs image data as well as additional data about thehost. Such information may include data from environmental sensors, suchas ambient light or temperature; information about the host, including,for example, an operating mode of the host or the amount of powerremaining in the host's power source; information about the content ofthe image data; information about the type of image data; and/orinstructions for display apparatus for use in selecting an imaging mode.

The user input module 126 conveys the personal preferences of the userto the controller 134, either directly, or via the host processor 122.In some implementations, the user input module 126 is controlled bysoftware in which the user programs personal preferences such as “deepercolor,” “better contrast,” “lower power,” “increased brightness,”“sports,” “live action,” or “animation.” In some other implementations,these preferences are input to the host using hardware, such as a switchor dial. The plurality of data inputs to the controller 134 direct thecontroller to provide data to the various drivers 130, 132, 138 and 148which correspond to optimal imaging characteristics.

An environmental sensor module 124 also can be included as part of thehost device 120. The environmental sensor module 124 receives data aboutthe ambient environment, such as temperature and or ambient lightingconditions. The sensor module 124 can be programmed to distinguishwhether the device is operating in an indoor or office environmentversus an outdoor environment in bright daylight versus an outdoorenvironment at nighttime. The sensor module 124 communicates thisinformation to the display controller 134, so that the controller 134can optimize the viewing conditions in response to the ambientenvironment.

FIG. 2A shows a perspective view of an example shutter-based lightmodulator 200. The shutter-based light modulator 200 is suitable forincorporation into the direct-view MEMS-based display apparatus 100 ofFIG. 1A. The light modulator 200 includes a shutter 202 coupled to anactuator 204. The actuator 204 can be formed from two separate compliantelectrode beam actuators 205 (the “actuators 205”). The shutter 202couples on one side to the actuators 205. The actuators 205 move theshutter 202 transversely over a surface 203 in a plane of motion whichis substantially parallel to the surface 203. The opposite side of theshutter 202 couples to a spring 207 which provides a restoring forceopposing the forces exerted by the actuator 204.

Each actuator 205 includes a compliant load beam 206 connecting theshutter 202 to a load anchor 208. The load anchors 208 along with thecompliant load beams 206 serve as mechanical supports, keeping theshutter 202 suspended proximate to the surface 203. The surface 203includes one or more aperture holes 211 for admitting the passage oflight. The load anchors 208 physically connect the compliant load beams206 and the shutter 202 to the surface 203 and electrically connect theload beams 206 to a bias voltage, in some instances, ground.

If the substrate is opaque, such as silicon, then aperture holes 211 areformed in the substrate by etching an array of holes through thesubstrate 204. If the substrate 204 is transparent, such as glass orplastic, then the aperture holes 211 are formed in a layer oflight-blocking material deposited on the substrate 203. The apertureholes 211 can be generally circular, elliptical, polygonal, serpentine,or irregular in shape.

Each actuator 205 also includes a compliant drive beam 216 positionedadjacent to each load beam 206. The drive beams 216 couple at one end toa drive beam anchor 218 shared between the drive beams 216. The otherend of each drive beam 216 is free to move. Each drive beam 216 iscurved such that it is closest to the load beam 206 near the free end ofthe drive beam 216 and the anchored end of the load beam 206.

In operation, a display apparatus incorporating the light modulator 200applies an electric potential to the drive beams 216 via the drive beamanchor 218. A second electric potential may be applied to the load beams206. The resulting potential difference between the drive beams 216 andthe load beams 206 pulls the free ends of the drive beams 216 towardsthe anchored ends of the load beams 206, and pulls the shutter ends ofthe load beams 206 toward the anchored ends of the drive beams 216,thereby driving the shutter 202 transversely toward the drive anchor218. The compliant members 206 act as springs, such that when thevoltage across the beams 206 and 216 potential is removed, the loadbeams 206 push the shutter 202 back into its initial position, releasingthe stress stored in the load beams 206.

A light modulator, such as the light modulator 200, incorporates apassive restoring force, such as a spring, for returning a shutter toits rest position after voltages have been removed. Other shutterassemblies can incorporate a dual set of “open” and “closed” actuatorsand a separate set of “open” and “closed” electrodes for moving theshutter into either an open or a closed state.

There are a variety of methods by which an array of shutters andapertures can be controlled via a control matrix to produce images, inmany cases moving images, with appropriate luminance levels. In somecases, control is accomplished by means of a passive matrix array of rowand column interconnects connected to driver circuits on the peripheryof the display. In other cases it is appropriate to include switchingand/or data storage elements within each pixel of the array (theso-called active matrix) to improve the speed, the luminance leveland/or the power dissipation performance of the display.

The display apparatus 100, in alternative implementations, includesdisplay elements other than transverse shutter-based light modulators,such as the shutter assembly 200 described above.

FIG. 2B shows an example cross sectional view of an illustrative nonshutter-based MEMS light modulator 250. The light tap modulator 250 issuitable for incorporation into an alternative implementation of theMEMS-based display apparatus 100 of FIG. 1A. A light tap works accordingto a principle of frustrated total internal reflection (TIR). That is,light 252 is introduced into a light guide 254, in which, withoutinterference, light 252 is, for the most part, unable to escape thelight guide 254 through its front or rear surfaces due to TIR. The lighttap 250 includes a tap element 256 that has a sufficiently high index ofrefraction that, in response to the tap element 256 contacting the lightguide 254, the light 252 impinging on the surface of the light guide 254adjacent the tap element 256 escapes the light guide 254 through the tapelement 256 towards a viewer, thereby contributing to the formation ofan image.

In some implementations, the tap element 256 is formed as part of a beam258 of flexible, transparent material. Electrodes 260 coat portions ofone side of the beam 258. Opposing electrodes 262 are disposed on thelight guide 254. By applying a voltage across the electrodes 260 and262, the position of the tap element 256 relative to the light guide 254can be controlled to selectively extract light 252 from the light guide254.

FIG. 3A shows an example schematic diagram of a control matrix 300. Thecontrol matrix 300 is suitable for controlling the light modulatorsincorporated into the MEMS-based display apparatus 100 of FIG. 1A. FIG.3B shows a perspective view of an example array 320 of shutter-basedlight modulators connected to the control matrix 300 of FIG. 3A. Thecontrol matrix 300 may address an array of pixels 320 (the “array 320”).Each pixel 301 can include an elastic shutter assembly 302, such as theshutter assembly 200 of FIG. 2A, controlled by an actuator 303. Eachpixel also can include an aperture layer 322 that includes apertures324.

The control matrix 300 is fabricated as a diffused orthin-film-deposited electrical circuit on the surface of a substrate 304on which the shutter assemblies 302 are formed. The control matrix 300includes a scan-line interconnect 306 for each row of pixels 301 in thecontrol matrix 300 and a data-interconnect 308 for each column of pixels301 in the control matrix 300. Each scan-line interconnect 306electrically connects a write-enabling voltage source 307 to the pixels301 in a corresponding row of pixels 301. Each data interconnect 308electrically connects a data voltage source 309 (“V_(d) source”) to thepixels 301 in a corresponding column of pixels. In the control matrix300, the V_(d) source 309 provides the majority of the energy to be usedfor actuation of the shutter assemblies 302. Thus, the data voltagesource, V_(d) source 309, also serves as an actuation voltage source.

Referring to FIGS. 3A and 3B, for each pixel 301 or for each shutterassembly 302 in the array of pixels 320, the control matrix 300 includesa transistor 310 and a capacitor 312. The gate of each transistor 310 iselectrically connected to the scan-line interconnect 306 of the row inthe array 320 in which the pixel 301 is located. The source of eachtransistor 310 is electrically connected to its corresponding datainterconnect 308. The actuators 303 of each shutter assembly 302 includetwo electrodes. The drain of each transistor 310 is electricallyconnected in parallel to one electrode of the corresponding capacitor312 and to one of the electrodes of the corresponding actuator 303. Theother electrode of the capacitor 312 and the other electrode of theactuator 303 in shutter assembly 302 are connected to a common or groundpotential. In alternate implementations, the transistors 310 can bereplaced with semiconductor diodes and or metal-insulator-metal sandwichtype switching elements.

In operation, to form an image, the control matrix 300 write-enableseach row in the array 320 in a sequence by applying V_(we) to eachscan-line interconnect 306 in turn. For a write-enabled row, theapplication of V_(we) to the gates of the transistors 310 of the pixels301 in the row allows the flow of current through the data interconnects308 through the transistors 310 to apply a potential to the actuator 303of the shutter assembly 302. While the row is write-enabled, datavoltages V_(d) are selectively applied to the data interconnects 308. Inimplementations providing analog gray scale, the data voltage applied toeach data interconnect 308 is varied in relation to the desiredbrightness of the pixel 301 located at the intersection of thewrite-enabled scan-line interconnect 306 and the data interconnect 308.In implementations providing digital control schemes, the data voltageis selected to be either a relatively low magnitude voltage (i.e., avoltage near ground) or to meet or exceed V_(at) (the actuationthreshold voltage). In response to the application of V_(at) to a datainterconnect 308, the actuator 303 in the corresponding shutter assemblyactuates, opening the shutter in that shutter assembly 302. The voltageapplied to the data interconnect 308 remains stored in the capacitor 312of the pixel 301 even after the control matrix 300 ceases to applyV_(we) to a row. Therefore, the voltage V_(we) does not have to wait andhold on a row for times long enough for the shutter assembly 302 toactuate; such actuation can proceed after the write-enabling voltage hasbeen removed from the row. The capacitors 312 also function as memoryelements within the array 320, storing actuation instructions for theillumination of an image frame.

The pixels 301 as well as the control matrix 300 of the array 320 areformed on a substrate 304. The array 320 includes an aperture layer 322,disposed on the substrate 304, which includes a set of apertures 324 forrespective pixels 301 in the array 320. The apertures 324 are alignedwith the shutter assemblies 302 in each pixel. In some implementations,the substrate 304 is made of a transparent material, such as glass orplastic. In some other implementations, the substrate 304 is made of anopaque material, but in which holes are etched to form the apertures324.

The shutter assembly 302 together with the actuator 303 can be madebi-stable. That is, the shutters can exist in at least two equilibriumpositions (e.g., open or closed) with little or no power required tohold them in either position. More particularly, the shutter assembly302 can be mechanically bi-stable. Once the shutter of the shutterassembly 302 is set in position, no electrical energy or holding voltageis required to maintain that position. The mechanical stresses on thephysical elements of the shutter assembly 302 can hold the shutter inplace.

The shutter assembly 302 together with the actuator 303 also can be madeelectrically bi-stable. In an electrically bi-stable shutter assembly,there exists a range of voltages below the actuation voltage of theshutter assembly, which if applied to a closed actuator (with theshutter being either open or closed), holds the actuator closed and theshutter in position, even if an opposing force is exerted on theshutter. The opposing force may be exerted by a spring such as thespring 207 in the shutter-based light modulator 200 depicted in FIG. 2A,or the opposing force may be exerted by an opposing actuator, such as an“open” or “closed” actuator.

The light modulator array 320 is depicted as having a single MEMS lightmodulator per pixel. Other implementations are possible in whichmultiple MEMS light modulators are provided in each pixel, therebyproviding the possibility of more than just binary “on’ or “off” opticalstates in each pixel. Certain forms of coded area division gray scaleare possible where multiple MEMS light modulators in the pixel areprovided, and where apertures 324, which are associated with each of thelight modulators, have unequal areas.

In some other implementations, the roller-based light modulator 220, thelight tap 250, or the electrowetting-based light modulation array 270,as well as other MEMS-based light modulators, can be substituted for theshutter assembly 302 within the light modulator array 320.

FIGS. 4A and 4B show example views of a dual actuator shutter assembly400. The dual actuator shutter assembly 400, as depicted in FIG. 4A, isin an open state. FIG. 4B shows the dual actuator shutter assembly 400in a closed state. In contrast to the shutter assembly 200, the shutterassembly 400 includes actuators 402 and 404 on either side of a shutter406. Each actuator 402 and 404 is independently controlled. A firstactuator, a shutter-open actuator 402, serves to open the shutter 406. Asecond opposing actuator, the shutter-close actuator 404, serves toclose the shutter 406. Both of the actuators 402 and 404 are compliantbeam electrode actuators. The actuators 402 and 404 open and close theshutter 406 by driving the shutter 406 substantially in a plane parallelto an aperture layer 407 over which the shutter is suspended. Theshutter 406 is suspended a short distance over the aperture layer 407 byanchors 408 attached to the actuators 402 and 404. The inclusion ofsupports attached to both ends of the shutter 406 along its axis ofmovement reduces out of plane motion of the shutter 406 and confines themotion substantially to a plane parallel to the substrate. By analogy tothe control matrix 300 of FIG. 3A, a control matrix suitable for usewith the shutter assembly 400 might include one transistor and onecapacitor for each of the opposing shutter-open and shutter-closeactuators 402 and 404.

The shutter 406 includes two shutter apertures 412 through which lightcan pass. The aperture layer 407 includes a set of three apertures 409.In FIG. 4A, the shutter assembly 400 is in the open state and, as such,the shutter-open actuator 402 has been actuated, the shutter-closeactuator 404 is in its relaxed position, and the centerlines of theshutter apertures 412 coincide with the centerlines of two of theaperture layer apertures 409. In FIG. 4B the shutter assembly 400 hasbeen moved to the closed state and, as such, the shutter-open actuator402 is in its relaxed position, the shutter-close actuator 404 has beenactuated, and the light blocking portions of the shutter 406 are now inposition to block transmission of light through the apertures 409(depicted as dotted lines).

Each aperture has at least one edge around its periphery. For example,the rectangular apertures 409 have four edges. In alternativeimplementations in which circular, elliptical, oval, or other curvedapertures are formed in the aperture layer 407, each aperture may haveonly a single edge. In some other implementations, the apertures neednot be separated or disjoint in the mathematical sense, but instead canbe connected. That is to say, while portions or shaped sections of theaperture may maintain a correspondence to each shutter, several of thesesections may be connected such that a single continuous perimeter of theaperture is shared by multiple shutters.

In order to allow light with a variety of exit angles to pass throughapertures 412 and 409 in the open state, it is advantageous to provide awidth or size for shutter apertures 412 which is larger than acorresponding width or size of apertures 409 in the aperture layer 407.In order to effectively block light from escaping in the closed state,it is preferable that the light blocking portions of the shutter 406overlap the apertures 409. FIG. 4B shows a predefined overlap 416between the edge of light blocking portions in the shutter 406 and oneedge of the aperture 409 formed in the aperture layer 407.

The electrostatic actuators 402 and 404 are designed so that theirvoltage-displacement behavior provides a bi-stable characteristic to theshutter assembly 400. For each of the shutter-open and shutter-closeactuators there exists a range of voltages below the actuation voltage,which if applied while that actuator is in the closed state (with theshutter being either open or closed), will hold the actuator closed andthe shutter in position, even after an actuation voltage is applied tothe opposing actuator. The minimum voltage needed to maintain ashutter's position against such an opposing force is referred to as amaintenance voltage V_(m).

FIG. 5 shows an example cross sectional view of a display apparatus 500incorporating shutter-based light modulators (shutter assemblies) 502.Each shutter assembly 502 incorporates a shutter 503 and an anchor 505.Not shown are the compliant beam actuators which, when connected betweenthe anchors 505 and the shutters 503, help to suspend the shutters 503 ashort distance above the surface. The shutter assemblies 502 aredisposed on a transparent substrate 504, such a substrate made ofplastic or glass. A rear-facing reflective layer, reflective film 506,disposed on the substrate 504 defines a plurality of surface apertures508 located beneath the closed positions of the shutters 503 of theshutter assemblies 502. The reflective film 506 reflects light notpassing through the surface apertures 508 back towards the rear of thedisplay apparatus 500. The reflective aperture layer 506 can be afine-grained metal film without inclusions formed in thin film fashionby a number of vapor deposition techniques including sputtering,evaporation, ion plating, laser ablation, or chemical vapor deposition(CVD). In some other implementations, the rear-facing reflective layer506 can be formed from a mirror, such as a dielectric mirror. Adielectric mirror can be fabricated as a stack of dielectric thin filmswhich alternate between materials of high and low refractive index. Thevertical gap which separates the shutters 503 from the reflective film506, within which the shutter is free to move, is in the range of 0.5 to10 microns. The magnitude of the vertical gap is preferably less thanthe lateral overlap between the edge of shutters 503 and the edge ofapertures 508 in the closed state, such as the overlap 416 depicted inFIG. 4B.

The display apparatus 500 includes an optional diffuser 512 and/or anoptional brightness enhancing film 514 which separate the substrate 504from a planar light guide 516. The light guide 516 includes atransparent, i.e., glass or plastic material. The light guide 516 isilluminated by one or more light sources 518, forming a backlight. Thelight sources 518 can be, for example, and without limitation,incandescent lamps, fluorescent lamps, lasers or light emitting diodes(LEDs). A reflector 519 helps direct light from lamp 518 towards thelight guide 516. A front-facing reflective film 520 is disposed behindthe backlight 516, reflecting light towards the shutter assemblies 502.Light rays such as ray 521 from the backlight that do not pass throughone of the shutter assemblies 502 will be returned to the backlight andreflected again from the film 520. In this fashion light that fails toleave the display apparatus 500 to form an image on the first pass canbe recycled and made available for transmission through other openapertures in the array of shutter assemblies 502. Such light recyclinghas been shown to increase the illumination efficiency of the display.

The light guide 516 includes a set of geometric light redirectors orprisms 517 which re-direct light from the lamps 518 towards theapertures 508 and hence toward the front of the display. The lightredirectors 517 can be molded into the plastic body of light guide 516with shapes that can be alternately triangular, trapezoidal, or curvedin cross section. The density of the prisms 517 generally increases withdistance from the lamp 518.

In some implementations, the aperture layer 506 can be made of a lightabsorbing material, and in alternate implementations the surfaces ofshutter 503 can be coated with either a light absorbing or a lightreflecting material. In some other implementations, the aperture layer506 can be deposited directly on the surface of the light guide 516. Insome implementations, the aperture layer 506 need not be disposed on thesame substrate as the shutters 503 and anchors 505 (such as in theMEMS-down configuration described below).

In some implementations, the light sources 518 can include lamps ofdifferent colors, for instance, the colors red, green and blue. A colorimage can be formed by sequentially illuminating images with lamps ofdifferent colors at a rate sufficient for the human brain to average thedifferent colored images into a single multi-color image. The variouscolor-specific images are formed using the array of shutter assemblies502. In another implementation, the light source 518 includes lampshaving more than three different colors. For example, the light source518 may have red, green, blue and white lamps, or red, green, blue andyellow lamps. In some other implementations, the light source 518 mayinclude cyan, magenta, yellow and white lamps, red, green, blue andwhite lamps. In some other implementations, additional lamps may beincluded in the light source 518. For example, if using five colors, thelight source 518 may include red, green, blue, cyan and yellow lamps. Insome other implementations, the light source 518 may include white,orange, blue, purple and green lamps or white, blue, yellow, red andcyan lamps. If using six colors, the light source 518 may include red,green, blue, cyan, magenta and yellow lamps or white, cyan, magenta,yellow, orange and green lamps.

A cover plate 522 forms the front of the display apparatus 500. The rearside of the cover plate 522 can be covered with a black matrix 524 toincrease contrast. In alternate implementations the cover plate includescolor filters, for instance distinct red, green, and blue filterscorresponding to different ones of the shutter assemblies 502. The coverplate 522 is supported a predetermined distance away from the shutterassemblies 502 forming a gap 526. The gap 526 is maintained bymechanical supports or spacers 527 and/or by an adhesive seal 528attaching the cover plate 522 to the substrate 504.

The adhesive seal 528 seals in a fluid 530. The fluid 530 is engineeredwith viscosities preferably below about 10 centipoise and with relativedielectric constant preferably above about 2.0, and dielectric breakdownstrengths above about 10⁴ V/cm. The fluid 530 also can serve as alubricant. In some implementations, the fluid 530 is a hydrophobicliquid with a high surface wetting capability. In alternateimplementations, the fluid 530 has a refractive index that is eithergreater than or less than that of the substrate 504.

Displays that incorporate mechanical light modulators can includehundreds, thousands, or in some cases, millions of moving elements. Insome devices, every movement of an element provides an opportunity forstatic friction to disable one or more of the elements. This movement isfacilitated by immersing all the parts in a fluid (also referred to asfluid 530) and sealing the fluid (such as with an adhesive) within afluid space or gap in a MEMS display cell. The fluid 530 is usually onewith a low coefficient of friction, low viscosity, and minimaldegradation effects over the long term. When the MEMS-based displayassembly includes a liquid for the fluid 530, the liquid at leastpartially surrounds some of the moving parts of the MEMS-based lightmodulator. In some implementations, in order to reduce the actuationvoltages, the liquid has a viscosity below 70 centipoise. In some otherimplementations, the liquid has a viscosity below 10 centipoise. Liquidswith viscosities below 70 centipoise can include materials with lowmolecular weights: below 4000 grams/mole, or in some cases below 400grams/mole. Fluids 530 that also may be suitable for suchimplementations include, without limitation, de-ionized water, methanol,ethanol and other alcohols, paraffins, olefins, ethers, silicone oils,fluorinated silicone oils, or other natural or synthetic solvents orlubricants. Useful fluids can be polydimethylsiloxanes (PDMS), such ashexamethyldisiloxane and octamethyltrisiloxane, or alkyl methylsiloxanes such as hexylpentamethyldisiloxane. Useful fluids can bealkanes, such as octane or decane. Useful fluids can be nitroalkanes,such as nitromethane. Useful fluids can be aromatic compounds, such astoluene or diethylbenzene. Useful fluids can be ketones, such asbutanone or methyl isobutyl ketone. Useful fluids can be chlorocarbons,such as chlorobenzene. Useful fluids can be chlorofluorocarbons, such asdichlorofluoroethane or chlorotrifluoroethylene. Other fluids consideredfor these display assemblies include butyl acetate anddimethylformamide. Still other useful fluids for these displays includehydro fluoro ethers, perfluoropolyethers, hydro fluoro poly ethers,pentanol, and butanol. Example suitable hydro fluoro ethers includeethyl nonafluorobutyl ether and2-trifluoromethyl-3-ethoxydodecafluorohexane.

A sheet metal or molded plastic assembly bracket 532 holds the coverplate 522, the substrate 504, the backlight and the other componentparts together around the edges. The assembly bracket 532 is fastenedwith screws or indent tabs to add rigidity to the combined displayapparatus 500. In some implementations, the light source 518 is moldedin place by an epoxy potting compound. Reflectors 536 help return lightescaping from the edges of the light guide 516 back into the light guide516. Not depicted in FIG. 5 are electrical interconnects which providecontrol signals as well as power to the shutter assemblies 502 and thelamps 518.

In some other implementations, roller shade-based light modulator, thelight tap 250 shown in FIG. 2B, or other MEMS-based light modulators,can be substituted for the shutter assemblies 502 within the displayapparatus 500.

The display apparatus 500 is referred to as the MEMS-up configuration,wherein the MEMS based light modulators are formed on a front surface ofthe substrate 504, i.e., the surface that faces toward the viewer. Theshutter assemblies 502 are built directly on top of the reflectiveaperture layer 506. In an alternate implementation, referred to as theMEMS-down configuration, the shutter assemblies are disposed on asubstrate separate from the substrate on which the reflective aperturelayer is formed. The substrate on which the reflective aperture layer isformed, defining a plurality of apertures, is referred to herein as theaperture plate. In the MEMS-down configuration, the substrate thatcarries the MEMS-based light modulators takes the place of the coverplate 522 in the display apparatus 500 and is oriented such that theMEMS-based light modulators are positioned on the rear surface of thetop substrate, i.e., the surface that faces away from the viewer andtoward the light guide 516. The MEMS-based light modulators are therebypositioned directly opposite to and across a gap from the reflectiveaperture layer 506. The gap can be maintained by a series of spacerposts connecting the aperture plate and the substrate on which the MEMSmodulators are formed. In some implementations, the spacers are disposedwithin or between each pixel in the array. The gap or distance thatseparates the MEMS light modulators from their corresponding aperturesis preferably less than 10 microns, or a distance that is less than theoverlap between shutters and apertures, such as overlap 416.

FIG. 6 shows a cross sectional view of an example light modulatorsubstrate and an example aperture plate for use in a MEMS-downconfiguration of a display. The display assembly 600 includes amodulator substrate 602 and an aperture plate 604. The display assembly600 also includes a set of shutter assemblies 606 and a reflectiveaperture layer 608. The reflective aperture layer 608 includes apertures610. A predetermined gap or separation between the modulator substrates602 and the aperture plate 604 is maintained by the opposing set ofspacers 612 and 614. The spacers 612 are formed on or as part of themodulator substrate 602. The spacers 614 are formed on or as part of theaperture plate 604. During assembly, the two substrates 602 and 604 arealigned so that spacers 612 on the modulator substrate 602 make contactwith their respective spacers 614.

The separation or distance of this illustrative example is 8 microns. Toestablish this separation, the spacers 612 are 2 microns tall and thespacers 614 are 6 microns tall. Alternately, both spacers 612 and 614can be 4 microns tall, or the spacers 612 can be 6 microns tall whilethe spacers 614 are 2 microns tall. In fact, any combination of spacerheights can be employed as long as their total height establishes thedesired separation H12.

Providing spacers on both of the substrates 602 and 604, which are thenaligned or mated during assembly, has advantages with respect tomaterials and processing costs. The provision of a very tall, such aslarger than 8 micron spacers, can be costly as it can require relativelylong times for the cure, exposure, and development of a photo-imageablepolymer. The use of mating spacers as in display assembly 600 allows forthe use of thinner coatings of the polymer on each of the substrates.

In another implementation, the spacers 612 which are formed on themodulator substrate 602 can be formed from the same materials andpatterning blocks that were used to form the shutter assemblies 606. Forinstance, the anchors employed for shutter assemblies 606 also canperform a function similar to spacer 612. In this implementation, aseparate application of a polymer material to form a spacer would not berequired and a separate exposure mask for the spacers would not berequired.

FIG. 7 shows a plan view of an example array 700 of EMS display elements702 a-702 d (generally “display elements 702”). Each display element 702includes a shutter 704. Two compliant load beams 706 couple the shutter704 to respective shutter anchors 708. The shutter anchors 708 supportthe load beams 706 and the shutter 704 over a light blocking layer 707.Drive beams 710 are positioned adjacent to the respective load beams706. The drive beams 710 are supported over the light blocking layer 707by corresponding drive anchors 712.

Each load beam 706—drive beam 710 pair serves as an electrostaticactuator. Thus, each display element 702 includes two actuators: ashutter-open actuator and a shutter-close actuator. The actuators areconfigured to move their respective shutter 704 into and out ofalignment with a corresponding aperture 714 defined through the lightblocking layer 707 to modulate light. For example, the shutters 704 indisplay elements 702 a and 702 c are in a closed position, blockingtheir corresponding apertures 714. The shutters 704 in display elements702 b and 702 d, on the other hand, are in the open position, allowinglight to pass through their corresponding apertures 714.

The actuators are controlled by a control matrix, which may be similarto the control matrix 300 shown in FIG. 3A. The control matrix includedin the array 700 differs from the control matrix 300 in a few respects.First, the control matrix 300 was configured to control the shutterassemblies 200 shown in FIG. 2A. The shutter assemblies 200 onlyincluded a single actuator, whereas the display elements 702 depicted inFIG. 7 include both shutter-open and shutter-close actuators. As aresult the control matrix included in the array 700 includes circuitryfor controlling two actuators per display element 702, instead of onlyone. In addition, the control matrix in the array 700 omits a capacitorsimilar to the capacitor 312 shown in FIG. 3A. Instead, the displayelements 702 in FIG. 7 rely on the inherent capacitance of theircorresponding actuators.

Thus, the control matrix included in the array 700 includes awrite-enabling interconnect 720 for each row of display elements 702, ashutter-open data interconnect 722 and a shutter-close data interconnect724 for each column of display elements 702, and a common interconnect725 providing a shared ground voltage to display elements in multiplerows and multiple columns of display elements 702. The write-enablinginterconnect 720, the shutter open-interconnect 722, and theshutter-close interconnect 724 are electrically isolated from theshutter 704. The control matrix also includes two transistors 726 ineach display element 702, one for each actuator. In operation, thewrite-enabling interconnects 720 can be switched between being at aboutground and a write-enabling voltage of about 3V to about 7V. Theshutter-open and shutter-close interconnects 722 and 724 can be switchedbetween ground and an actuation voltage, V_(a), which, depending on thespecific configuration of the display element 702, ranges from about 15Vto about 40V.

The control matrix used to control the display elements 702 can beimplemented to operate similarly to the control matrix 300 shown in FIG.3A. More particularly, each row of shutter assemblies is addressed andactuated, one row at a time. To address and actuate a display element702, V_(we) is applied to the write-enabling interconnect 720corresponding to the row of the array 700 in which the display element702 is located. The write-enabling interconnect 720 couples to the gatesof the transistors 726 of the display elements 702 in its row. ApplyingV_(we) to the gate of the transistors 726 allows the actuators in thosedisplay elements 702 to respond to actuation voltages provided by theshutter-open and shutter-close interconnects 722 and 724. V_(a) is thenapplied to either the shutter-open interconnect 722 or the shutter-closeinterconnect 724 of the column in the array 700 in which the displayelement 702 is located, according to image data communicated to thearray 700. The application of V_(a) causes the respective displayelements 702 to move into a state indicated by the image data.

As shown in FIG. 7, the write-enabling and common interconnects 720 and725 pass directly under the load beams 706, the drive beams 710 and theshutter 704 of each display element 702. In addition, the shutter-openand shutter-close interconnects 722 and 724 pass underneath the drivebeams 710 of the display elements to which they couple in both the openand closed states. As shown in FIG. 7, when a display element 702 is inthe open state, the shutter-open interconnect 722 also passes under oneof the load beams 706 of the display element 702. Additionally, when adisplay element 702 is in a closed state, the shutter-close interconnect724 passes under the other load beam 706 of the display element 702. Insome other implementations, the shutter-close interconnects 722 mayalways pass under their corresponding load beams 706. In still someother implementations, the shutter-close interconnects may not passunder their corresponding load beams 706 in either the open or closedstates.

In some other implementations, other control matrix architectures anddesigns can be used. For example, only the write enabling interconnects720, or only the shutter-open or shutter-close interconnects 722 or 724are routed underneath suspended components of the display elements 702.Other control matrices may include either only one transistor perdisplay element or more than two transistors per display element.

In some other implementations, the control matrix includes separate datainterconnects and actuation interconnects, whereas the shutter-openinterconnects 722 and shutter-close interconnects 724 shown in FIG. 7effectively serve both roles. In some implementations incorporatingseparate data and actuation interconnects, both the data and actuationinterconnects are routed underneath one or more suspended components ofthe display elements 702. In some other implementations, only the datainterconnects, or only the actuation interconnects are routed under oneor more suspended components of the display elements 702.

In still other implementations, the control matrix in the array 700includes one or more switched global interconnects, such as a globalactuation interconnect, that couples to display elements in multiplerows and multiple columns of display elements. In such implementations,one or more of the global interconnects may be routed under one or moresuspended components of the display elements 702.

This control matrix configuration allows for greater display elementpacking density or increased aperture ratio, as less room is neededbetween display elements for electrical interconnects. However, havingthe interconnects 720,722 and 724 pass underneath the mechanicalcomponents (i.e., the load beams 706, the drive beams 710, and theshutters 704) of the display elements 702 increases the risk ofperformance degradation or device failure due to electrostaticattraction between the interconnects and the mechanical components andincreased interconnect capacitance. Various configurations of displayapparatus that include the array 700 of display elements 702, whilemitigating this risk, are disclosed below in relation to FIGS. 8-11.

FIGS. 8-11 show cross sectional views of example display apparatus800,900, 1000 and 1100 incorporating the array 700 of display elements702 shown in FIG. 7. FIGS. 8-10 show cross sections of display apparatusthat mitigate the risk posed by unwanted electrostatic attraction andincreased capacitance by introducing a relatively thick electricinsulation layer between the uppermost layer of the control matrix ofthe array 700 and the load beams 706, drive beams 710 and shutter 704 ofthe display elements 702. FIG. 11 mitigates the risk by increasing thedistance between the uppermost layer of the control matrix and the loadbeams 706, drive beams 710 and the shutter 704 of the display elements702 without including the thick layer of insulation.

FIG. 8 shows a cross sectional view of an example display apparatus 800incorporating the array 700 of display elements 702 shown in FIG. 7. Thecross-sectional view shown in FIG. 8 is taken along line A-A′ of FIG. 7.The display apparatus 800 is built in a MEMS-up configuration similar tothe display apparatus 500 shown in FIG. 5. That is, the array 700 isfabricated on a transparent substrate 802 positioned towards the rear ofthe display apparatus 800 and faces up towards a light blocking layer803 coupled to a cover sheet 804 that forms the front of the displayapparatus 800. The substrate 802 is positioned in front of a backlight806. Light emitted by the backlight 806 passes through apertures 714formed in the light blocking layer 707 to be modulated by the shutters704. While the backlight 806 is shown as being spaced apart from thesubstrate 802 in FIG. 8, in some other implementations, the twocomponents are in intimate contact or separated by only a very thin airgap.

In the display apparatus 800, the light blocking layer 707 includes twolayers, a reflective layer 808 and a light absorbing layer 810. Thereflective layer reflects light that escapes the backlight 806, butfails to pass through the apertures 714, back towards the backlight 806to be recycled. The light absorbing layer 810 absorbs light reflectingoff the rear-facing surfaces of the shutters 704, as well as strayambient light that may have entered the front of the display apparatus800.

The display apparatus 800 includes mechanical components and a controlmatrix 815. The mechanical components include the shutters 704, loadbeams 706, load anchors 708, drive beams 710, and drive anchors 712shown in FIG. 7.

In the control matrix 815, a first dielectric layer 812 separates thelight absorbing layer 810 from the write-enabling interconnects 720. Asecond dielectric layer 814 separates the write enabling interconnects720 from the shutter-open and shutter-close interconnects 722 and 724.The first and second dielectric layers 812 and 814 are deposited insubstantially conforming layers using a CVD plasma-enhanced chemicalvapor deposition (PECVD), or other vapor deposition process tothicknesses of between about 0.1 microns and about 1 micron. They may beformed using any standard inter-metal dielectric (IMD) material commonlyused in thin-film fabrication, such as silicon nitrides (SiN_(x)),silicon dioxide (SiO₂), or organic thin film layers, and for exampleplanarization layers made of acrylics. In some implementations, the IMDis selected to be transparent, such as SiN_(x), SiO₂, or one of theacrylic organic materials described above, such that its interferencewith the optical path through the apertures 714 of the display apparatus800 are minimized. In some implementations, the IMD is selected to havean index of refraction that matches the substrate 802 and/or a fluidthat fills the display apparatus 800, to reduce any reflections thatmight occur at the interface between the IMD and the fluid or the IMDand the substrate 802, respectively. In implementations in which the IMDis light absorbing and/or has a substantially different index ofrefraction than the substrate or the fluid, the IMD is removed fromabove the apertures 714, except where the IMD serves to insulate aninterconnect crossing the apertures 714.

To reduce the strength of the electric field 816 between the switchedinterconnects (i.e., the write-enabling interconnects 720, theshutter-open interconnects 722, and the shutter-close interconnects 724)and the suspend components (i.e., the shutters 704, load beams 706, anddrive beams 708) of the display elements 702, the display apparatus 800includes a relatively thick layer of electrically insulating material818. In some implementations, the electrically insulating material 818is deposited using a spin-on process such that it also serves as aplanarization layer to provide an even surface on which the fabricatethe structural components of the display apparatus 800. A thinpassivation layer 820 is then deposited on all exposed surfaces of thearray 700.

In some implementations, the layer of electrically insulating material818 is a dielectric. As with the IMD materials, in some implementations,the electrically insulating material 818 is chosen to be bothtransparent and to have an index of refraction that substantiallymatches the index of refraction of the substrate 802 and/or the fluid.In some other implementations, the electrically insulating material 818is light absorbing and/or has a substantially different index ofrefraction than the substrate or the fluid. In such implementations, theelectrically insulating material 818 is removed through an etching stepfrom above the apertures 714, except where the electrically insulatingmaterial 818 serves to insulate an interconnect crossing the apertures714. In some implementations, the electrically insulating material 818is the same dielectric material used to form the first and seconddielectric layers 812 and 814. The layer of electrically insulatingmaterial 818 decreases the strength of the electric field 816 both byits material properties, and by providing additional distance betweenthe switched interconnects and the suspended components. Depending onthe dielectric constant of the electrically insulating material 818, thedielectric constant of any other intervening medium between theelectrically insulation material 818 and the suspended components of thedisplay elements 702, and the gap between the switched interconnects andthe suspended components, the electrically insulating material 818 alsomay reduce the capacitance of the interconnects. Accordingly, in someimplementations, the electrically insulating material is selected suchthat it has a dielectric constant that is less than the dielectricconstant of a fluid surrounding the display elements 702.

In some implementations, the layer of electrically insulating material818 has a thickness ranging from greater than about 1 micron up to about5 microns. In some other implementations, the layer of electricallyinsulating material 818 is between about 1.5 and about 4 microns thick.In some other implementations, the layer of electrically insulatingmaterial 818 is between about 2 and about 4 microns thick. In some otherimplementations, the layer of electrically insulating material 818 isabout 3 microns thick. In some implementations, the suspended componentsof the display elements 702 are suspended at least 2 microns and lessthan 7 microns above the layer of electrically insulating material 818.In some other implementations, the suspended components are suspendedbetween 4 and about 5 microns over the layer of electrically insulatingmaterial 818. In some implementations, the total distance in a directionnormal to the substrate 802 between the uppermost switched interconnectand the closest suspended component is greater than about 3 microns andless than about 12 microns. In some other implementations, the totaldistance is between about 5 and about 9 microns.

FIG. 9 shows a cross sectional view of another example display apparatus900 including the array 700 of display elements 702 shown in FIG. 7. Thecross-sectional view is taken along the line B-B′ in FIG. 7. The displayapparatus 900 is similar to the display apparatus 800 of FIG. 8.However, in contrast to the display apparatus 800, the display apparatus900 includes an elevated integrated aperture layer 901. The elevatedintegrated aperture layer 901 helps prevent stray light that bounces offthe undersides of the shutters 704 from reaching the front of, andescaping, the display apparatus 900, thus improving the contrast ratioof the display apparatus 900.

The elevated integrated aperture layer 901 is supported over a rearsubstrate 902, on which the array 700 is fabricated, by pairs ofaperture layer anchors 904. In some implementations, the elevatedintegrated aperture layer 901 is supported between about 1 and about 5microns over the surface of the shutters 704 closest to the elevatedintegrated aperture layer 901. In some other implementations, theelevated integrated aperture layer 901 is supported between about 2 andabout 4 microns over the surface of the shutters 704. In some otherimplementations, the elevated integrated aperture layer 901 is supportedabout 3 microns over the surface of the shutters 704.

Like the display apparatus 800 shown in FIG. 8, the display apparatus900 shown in FIG. 9 includes a two-layer light absorbing layer 707,including a light reflective layer 808 and a light absorbing layer 810.The display apparatus 900 also includes a control matrix 915. Thecontrol matrix 915 includes first and second layers of dielectricmaterial 812 and 814 formed from one or more IMD materials, and thethick layer of electrically insulating material 818. The second layer ofdielectric material 814 is not visible in FIG. 9, as, duringfabrication, the second layer of dielectric material 814 is etched awayexcept where used to insulate the write-enabling interconnects 720,which are not present in the depicted cross section. The IMDs used inFIG. 9, as well as the electrically insulating material 818 are lightabsorbing. Therefore, they have been etched away over the aperture 720.In some other implementations, the IMDs and the electrically insulatingmaterial 818 are transparent. In such implementations, they may be leftover the aperture 720. The thicknesses of the first and seconddielectric layers 812 and 814 as well as the layer of electricallyinsulating material 818 can be the same as those set forth above withrespect to the display apparatus 800.

FIG. 10 shows a cross section of yet another example display apparatus1000 incorporating the array 700 of display elements 702 shown in FIG.7. The cross-sectional view is also taken along line B-B′ in FIG. 7. Incontrast to the display apparatus 900, the display apparatus 1000 lacksan elevated integrated aperture layer. As such, FIG. 10 omits both theelevated integrated aperture layer 901 as well as the aperture layeranchors 904 shown in FIG. 9.

In addition, unlike the display apparatus 800 and 900 shown in FIGS. 8and 9, the display apparatus 1000 shown in FIG. 10 is built in aMEMS-down configuration. That is, the array 700 is fabricated on a frontsubstrate 1002 of the display apparatus 1000, facing back towards abacklight 1004. As a result, the light blocking layer 707 only includesa light absorbing layer 908. The display apparatus 1000 also includes aseparate aperture plate substrate 1010 positioned between the array 700and the backlight 1004. A second light blocking layer 1012 is formed onthe aperture plate substrate 1010. This second light blocking layer 1012includes a light reflecting layer 1014 and a light absorbing layer 1016.

Like the display apparatus 800 and 900, the display apparatus 1000includes the relatively thick layer of electrically insulating material818 deposited over the control matrix incorporated into the array 700.

FIG. 11 shows a cross-sectional view of yet another display apparatus1100, which incorporates the array 700 of display elements 702 shown inFIG. 7. The cross-sectional view shown in FIG. 11 is taken along lineC-C′ shown in FIG. 7. Like the display apparatus 800 and 900, shown inFIGS. 8 and 9, the display apparatus 1100 is fabricated in a MEMS-upconfiguration. Accordingly, the array 700 is formed on a rear substrate1102, proximate to a backlight 1104, and faces up towards a cover sheet1106 at the front of the display apparatus 1100.

In contrast to the display apparatus 800, 900 and 1000 shown in FIGS. 8,9 and 10, respectively, the display apparatus 1100 omits the thickerlayer of electrically insulating material 818. Instead, the displayapparatus 1100 relies solely on an increased distance between theuppermost interconnect of the control matrix 1101 incorporated into thearray 700 and the suspended components of its display elements 702, toreduce the risk posed by undesirable electric fields and performancedegradation results from increased capacitance. As such, the displayapparatus 1100 includes taller load and drive anchors 708 and 712 thanwere included in the display apparatus 800, 900, and 100. With thetaller anchors 708 and 712, the distance normal to the plane of thesubstrate 1102 between the uppermost interconnect in the control matrixand the and the nearest suspended components in the array 700, like inthe display apparatus 800, 900, and 1000, is greater than about 3microns and less than about 12 microns. In some other implementations,the total distance is between about 5 and about 9 microns. In some otherimplementations, the total distance is about 7 microns.

Like the control matrices 815 and 915 incorporated into the displayapparatus 800 and 900, the control matrix 1101 includes first and seconddielectric layers 812 and 814 deposited on top of the light blockinglayer 707 and the write-enabling interconnects 720 (not shown),respectively. Since the control matrix 1101 omits the thicker layer ofelectrically insulating material 818, the control matrix 1101 includes athird layer of dielectric material 1110, having a standard IMD layerthickness, such as between about 0.1 microns and about 1 microndeposited over the shutter-open and shutter-close interconnects 722 and724. The dielectric layers 812, 814 and 1110 are formed usingtransparent IMD materials. Thus, the IMD materials forming the first,second and third dielectric layers 812, 814 and 816 are preserved overthe apertures 714 defined in the light blocking layer 707, avoidingextra patterning steps and reducing the cost of manufacture of thedisplay apparatus 1100. In addition, at least the first dielectric layer812 is deposited using a spin-on process, instead of more costly CVD orPECVD processes. In some other implementations, the layers of dielectricmaterial are formed using conformal deposition processes and/or usinglight absorbing IMD materials.

FIGS. 12 and 13 are example system block diagrams illustrating a displaydevice 40 that includes a plurality of display elements. The displaydevice 40 can be, for example, a smart phone, a cellular or mobiletelephone. However, the same components of the display device 40 orslight variations thereof are also illustrative of various types ofdisplay devices such as televisions, computers, tablets, e-readers,hand-held devices and portable media devices.

The display device 40 includes a housing 41, a display 30, an antenna43, a speaker 45, an input device 48 and a microphone 46. The housing 41can be formed from any of a variety of manufacturing processes,including injection molding, and vacuum forming. In addition, thehousing 41 may be made from any of a variety of materials, including,but not limited to: plastic, metal, glass, rubber and ceramic, or acombination thereof. The housing 41 can include removable portions (notshown) that may be interchanged with other removable portions ofdifferent color, or containing different logos, pictures, or symbols.

The display 30 may be any of a variety of displays, including abi-stable or analog display, as described herein. The display 30 alsocan be configured to include a flat-panel display, such as plasma,electroluminescent (EL) displays, OLED, super twisted nematic (STN)display, LCD, or thin-film transistor (TFT) LCD, or a non-flat-paneldisplay, such as a cathode ray tube (CRT) or other tube device. Inaddition, the display 30 can include a mechanical light modulator-baseddisplay, as described herein.

The components of the display device 40 are schematically illustrated inFIG. 12. The display device 40 includes a housing 41 and can includeadditional components at least partially enclosed therein. For example,the display device 40 includes a network interface 27 that includes anantenna 43 which can be coupled to a transceiver 47. The networkinterface 27 may be a source for image data that could be displayed onthe display device 40. Accordingly, the network interface 27 is oneexample of an image source module, but the processor 21 and the inputdevice 48 also may serve as an image source module. The transceiver 47is connected to a processor 21, which is connected to conditioninghardware 52. The conditioning hardware 52 may be configured to conditiona signal (such as filter or otherwise manipulate a signal). Theconditioning hardware 52 can be connected to a speaker 45 and amicrophone 46. The processor 21 also can be connected to an input device48 and a driver controller 29. The driver controller 29 can be coupledto a frame buffer 28, and to an array driver 22, which in turn can becoupled to a display array 30. One or more elements in the displaydevice 40, including elements not specifically depicted in FIG. 12, canbe configured to function as a memory device and be configured tocommunicate with the processor 21. In some implementations, a powersupply 50 can provide power to substantially all components in theparticular display device 40 design.

The network interface 27 includes the antenna 43 and the transceiver 47so that the display device 40 can communicate with one or more devicesover a network. The network interface 27 also may have some processingcapabilities to relieve, for example, data processing requirements ofthe processor 21. The antenna 43 can transmit and receive signals. Insome implementations, the antenna 43 transmits and receives RF signalsaccording to the IEEE 16.11 standard, including IEEE 16.11(a), (b), or(g), or the IEEE 802.11 standard, including IEEE 802.11a, b, g, n, andfurther implementations thereof. In some other implementations, theantenna 43 transmits and receives RF signals according to the Bluetooth®standard. In the case of a cellular telephone, the antenna 43 can bedesigned to receive code division multiple access (CDMA), frequencydivision multiple access (FDMA), time division multiple access (TDMA),Global System for Mobile communications (GSM), GSM/General Packet RadioService (GPRS), Enhanced Data GSM Environment (EDGE), TerrestrialTrunked Radio (TETRA), Wideband-CDMA (W-CDMA), Evolution Data Optimized(EV-DO), 1xEV-DO, EV-DO Rev A, EV-DO Rev B, High Speed Packet Access(HSPA), High Speed Downlink Packet Access (HSDPA), High Speed UplinkPacket Access (HSUPA), Evolved High Speed Packet Access (HSPA+), LongTerm Evolution (LTE), AMPS, or other known signals that are used tocommunicate within a wireless network, such as a system utilizing 3G, 4Gor 5G technology. The transceiver 47 can pre-process the signalsreceived from the antenna 43 so that they may be received by and furthermanipulated by the processor 21. The transceiver 47 also can processsignals received from the processor 21 so that they may be transmittedfrom the display device 40 via the antenna 43.

In some implementations, the transceiver 47 can be replaced by areceiver. In addition, in some implementations, the network interface 27can be replaced by an image source, which can store or generate imagedata to be sent to the processor 21. The processor 21 can control theoverall operation of the display device 40. The processor 21 receivesdata, such as compressed image data from the network interface 27 or animage source, and processes the data into raw image data or into aformat that can be readily processed into raw image data. The processor21 can send the processed data to the driver controller 29 or to theframe buffer 28 for storage. Raw data typically refers to theinformation that identifies the image characteristics at each locationwithin an image. For example, such image characteristics can includecolor, saturation and gray-scale level.

The processor 21 can include a microcontroller, CPU, or logic unit tocontrol operation of the display device 40. The conditioning hardware 52may include amplifiers and filters for transmitting signals to thespeaker 45, and for receiving signals from the microphone 46. Theconditioning hardware 52 may be discrete components within the displaydevice 40, or may be incorporated within the processor 21 or othercomponents.

The driver controller 29 can take the raw image data generated by theprocessor 21 either directly from the processor 21 or from the framebuffer 28 and can re-format the raw image data appropriately for highspeed transmission to the array driver 22. In some implementations, thedriver controller 29 can re-format the raw image data into a data flowhaving a raster-like format, such that it has a time order suitable forscanning across the display array 30. Then the driver controller 29sends the formatted information to the array driver 22. Although adriver controller 29, such as an LCD controller, is often associatedwith the system processor 21 as a stand-alone Integrated Circuit (IC),such controllers may be implemented in many ways. For example,controllers may be embedded in the processor 21 as hardware, embedded inthe processor 21 as software, or fully integrated in hardware with thearray driver 22.

The array driver 22 can receive the formatted information from thedriver controller 29 and can re-format the video data into a parallelset of waveforms that are applied many times per second to the hundreds,and sometimes thousands (or more), of leads coming from the display'sx-y matrix of display elements. In some implementations, the arraydriver 22 and the display array 30 are a part of a display module. Insome implementations, the driver controller 29, the array driver 22, andthe display array 30 are a part of the display module.

In some implementations, the driver controller 29, the array driver 22,and the display array 30 are appropriate for any of the types ofdisplays described herein. For example, the driver controller 29 can bea conventional display controller or a bi-stable display controller(such as a mechanical light modulator display element controller).Additionally, the array driver 22 can be a conventional driver or abi-stable display driver (such as a mechanical light modulator displayelement controller). Moreover, the display array 30 can be aconventional display array or a bi-stable display array (such as adisplay including an array of mechanical light modulator displayelements). In some implementations, the driver controller 29 can beintegrated with the array driver 22. Such an implementation can beuseful in highly integrated systems, for example, mobile phones,portable-electronic devices, watches or small-area displays.

In some implementations, the input device 48 can be configured to allow,for example, a user to control the operation of the display device 40.The input device 48 can include a keypad, such as a QWERTY keyboard or atelephone keypad, a button, a switch, a rocker, a touch-sensitivescreen, a touch-sensitive screen integrated with the display array 30,or a pressure- or heat-sensitive membrane. The microphone 46 can beconfigured as an input device for the display device 40. In someimplementations, voice commands through the microphone 46 can be usedfor controlling operations of the display device 40.

The power supply 50 can include a variety of energy storage devices. Forexample, the power supply 50 can be a rechargeable battery, such as anickel-cadmium battery or a lithium-ion battery. In implementationsusing a rechargeable battery, the rechargeable battery may be chargeableusing power coming from, for example, a wall socket or a photovoltaicdevice or array. Alternatively, the rechargeable battery can bewirelessly chargeable. The power supply 50 also can be a renewableenergy source, a capacitor, or a solar cell, including a plastic solarcell or solar-cell paint. The power supply 50 also can be configured toreceive power from a wall outlet.

In some implementations, control programmability resides in the drivercontroller 29 which can be located in several places in the electronicdisplay system. In some other implementations, control programmabilityresides in the array driver 22. The above-described optimization may beimplemented in any number of hardware and/or software components and invarious configurations.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The various illustrative logics, logical blocks, modules, circuits andalgorithm processes described in connection with the implementationsdisclosed herein may be implemented as electronic hardware, computersoftware, or combinations of both. The interchangeability of hardwareand software has been described generally, in terms of functionality,and illustrated in the various illustrative components, blocks, modules,circuits and processes described above. Whether such functionality isimplemented in hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

The hardware and data processing apparatus used to implement the variousillustrative logics, logical blocks, modules and circuits described inconnection with the aspects disclosed herein may be implemented orperformed with a general purpose single- or multi-chip processor, adigital signal processor (DSP), an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof designed to perform thefunctions described herein. A general purpose processor may be amicroprocessor, or, any conventional processor, controller,microcontroller, or state machine. A processor also may be implementedas a combination of computing devices, e.g., a combination of a DSP anda microprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration. In some implementations, particular processes and methodsmay be performed by circuitry that is specific to a given function.

In one or more aspects, the functions described may be implemented inhardware, digital electronic circuitry, computer software, firmware,including the structures disclosed in this specification and theirstructural equivalents thereof, or in any combination thereof.Implementations of the subject matter described in this specificationalso can be implemented as one or more computer programs, i.e., one ormore modules of computer program instructions, encoded on a computerstorage media for execution by, or to control the operation of, dataprocessing apparatus.

Various modifications to the implementations described in thisdisclosure may be readily apparent to those skilled in the art, and thegeneric principles defined herein may be applied to otherimplementations without departing from the spirit or scope of thisdisclosure. Thus, the claims are not intended to be limited to theimplementations shown herein, but are to be accorded the widest scopeconsistent with this disclosure, the principles and the novel featuresdisclosed herein.

Additionally, a person having ordinary skill in the art will readilyappreciate, the terms “upper” and “lower” are sometimes used for ease ofdescribing the figures, and indicate relative positions corresponding tothe orientation of the figure on a properly oriented page, and may notreflect the proper orientation of any device as implemented.

Certain features that are described in this specification in the contextof separate implementations also can be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation also can be implemented inmultiple implementations separately or in any suitable subcombination.Moreover, although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Further, the drawings may schematically depict one more exampleprocesses in the form of a flow diagram. However, other operations thatare not depicted can be incorporated in the example processes that areschematically illustrated. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the illustrated operations. In certain circumstances,multitasking and parallel processing may be advantageous. Moreover, theseparation of various system components in the implementations describedabove should not be understood as requiring such separation in allimplementations, and it should be understood that the described programcomponents and systems can generally be integrated together in a singlesoftware product or packaged into multiple software products.Additionally, other implementations are within the scope of thefollowing claims. In some cases, the actions recited in the claims canbe performed in a different order and still achieve desirable results.

What is claimed is:
 1. An apparatus comprising: an array of displayelements each having suspended components including a movable lightblocking component and a conductive beam coupled to the movable lightblocking component; a control matrix including a plurality ofinterconnects, including at least one switched interconnect whichcouples to portions of a plurality of the display elements in the array,passes under at least one of the conductive beam and the movable lightblocking components, and which is electrically isolated from the movablelight blocking components; and an electrical insulation layer having athickness greater than about 1 micron and less than about 5 microns,disposed between the at least one switched interconnect and thesuspended components of the display elements.
 2. The apparatus of claim1, wherein the electrical insulation layer is disposed between anuppermost interconnect of the control matrix and the suspendedcomponents of the display apparatus.
 3. The apparatus of claim 1,wherein the conductive beam of each of the display elements is coupledto an anchor, and the electric insulation layer is disposed under theanchors supporting the conductive beams of the display elements.
 4. Theapparatus of claim 1, wherein the electric insulation layer has athickness of greater than about 1.5 microns and less than about 4microns.
 5. The apparatus of claim 1, wherein the electrical insulationlayer has a thickness of greater than about 2 microns and less thanabout 4 microns.
 6. The apparatus of claim 1, further comprising a lightblocking layer positioned between the light-blocking component and abacklight, wherein the switched interconnect is disposed over the lightblocking layer.
 7. The apparatus of claim 6, wherein the light blockinglayer includes a plurality of openings, and the light blocking componentof each display element is configured to move into and out of alignmentwith a corresponding opening in the light blocking layer.
 8. Theapparatus of claim 7, wherein the electric insulation layer extends overthe plurality of openings.
 9. The apparatus of claim 1, wherein theswitched interconnect includes one of a data interconnect, awrite-enabling interconnect, and an actuation voltage interconnect. 10.The apparatus of claim 1, wherein the switched interconnect includes aninterconnect coupled to display elements in multiple rows and multiplecolumns of the array of display elements.
 11. The apparatus of claim 1,wherein the electric insulation layer is light absorbing.
 12. Theapparatus of claim 1, wherein the electric insulation layer issubstantially transparent.
 13. The apparatus of claim 1, comprising: adisplay; a processor that is configured to communicate with the display,the processor being configured to process image data; and a memorydevice that is configured to communicate with the processor.
 14. Theapparatus of claim 13, the display further including: a driver circuitconfigured to send at least one signal to the display; and a controllerconfigured to send at least a portion of the image data to the drivercircuit.
 15. The apparatus of claim 13, the display further including:an image source module configured to send the image data to theprocessor, wherein the image source module comprises at least one of areceiver, transceiver, and transmitter.
 16. The apparatus of claim 13,the display further including: an input device configured to receiveinput data and to communicate the input data to the processor.
 17. Adisplay device, comprising: an array of display elements each includinga light modulating means; a control matrix including a plurality ofinterconnects, including at least one switched interconnect whichcouples to portions of a plurality of the display elements in the array,passes under at least a portion of the light modulating means, and whichis electrically isolated from the light modulating means; and a meansfor reducing the strength of an electric field emanating from theswitched interconnect on the light modulating means.
 18. The displaydevice of claim 17, wherein the light modulating means includes a lightblocking shutter suspended over a substrate by a compliant beam.
 19. Thedisplay device of claim 17, wherein the means for reducing the strengthof the electric field includes an electric insulation layer disposedbetween the switched interconnect and the light modulating means. 20.The display device of claim 17, wherein the electric insulation layerhas a thickness greater than about 1 micron and less than about 5microns.
 21. The display device of claim 17, including means forreducing the capacitance of the interconnects in the control matrix. 22.The display device of claim 21, wherein the means for reducing thecapacitance of the interconnects includes the means for reducing thestrength of the electric field.